1. Field of the Invention
The present invention relates to a programmable controller system configured to notify deterioration diagnosis result of an external equipment implemented by a remote input/output apparatus to a programmable controller apparatus via communication path, so that the deterioration diagnosis result can be referred directly with a ladder diagram.
2. Description of the Related Art
Prior to this application, the applicant has proposed a programmable controller system (hereinafter, referred to as PLC system) configured to notify deterioration diagnosis result of an external equipment implemented by a remote input/output apparatus to a programmable controller apparatus via communication path, so that the deterioration diagnosis result can be referred (for example, see Japanese Patent Application Laid-Open No. 2003-295914).
According to such PLC system, as conventional, message communication process for retrieving data related to deterioration diagnosis from a remote input/output apparatus is not required to be loaded to user program of the PLC. Accordingly, various effects are achieved such that effort for producing user program is reduced, or delay of cycle time due to executing such maintenance user program executed simultaneously with the original control user program is reduced.
This type of external equipment deterioration diagnosis is configured to obtain time lag between a predetermined signal edge (raising edge or falling edge) of one terminal constituting each of one or more input/output terminal (for example OUT1 and IN1, IN1 and IN2, . . . ) of a remote input/output apparatus and a predetermined signal edge (raising edge or falling edge) of the other terminal, generate deterioration characteristic amount based on the one or more time lag data obtained in such manner (in case of one pair of terminals, the deterioration characteristic amount may be the time lag itself), and compares the deterioration characteristic amount with a predetermined deterioration determination threshold value (TH) in order to diagnose and predict deterioration of an external equipment relative to the pairs of terminals. Here, the threshold value (TH) may include a higher threshold value (TH-H) and a lower threshold value (TH-L).
When such deterioration diagnosis function is included in a slave of the PLC system, for example, it is connected to an external equipment so as to load sensor inputs at IN1 starting with the operation complete position of the external equipment at the timing of activating the external equipment at OUT1, thus enabling obtaining the operation time of the external equipment. Accordingly, by comparing the operation time with the predetermined deterioration diagnosis threshold value, serial deterioration diagnosis is realized for the external equipment (which may be a specific actuator or a series of operative mechanism including a specific actuator).
In order to introduce such external equipment deterioration diagnosis function to the PLC system, a proper deterioration diagnosis threshold value (TH, or TH-H and TH-L) is needed to be determined in advance. For this, process for storing (so-called logging process) is required to store measurement values of time lag relative to each relevant pair of terminals (measurement value is obtained by the remote input/output apparatus itself while operating the PLC apparatus and the remote input/output apparatus in actual. The logging process sometimes requires one or two month according to types of the apparatus or system to be controlled.
Conventionally, the logging process is carried out by installing a logging program, which is for transferring time lag data generated in the remote input/output apparatus to the PLC apparatus and storing in the user program itself of the PLC apparatus constituting the PLC system.
FIG. 10 is a ladder diagram showing an example of user program for such logging program. This program is configured to obtain time lag (T1) between a predetermined signal edges of a first pair of terminals (OUT1 and IN1) and time lag (T2) between a predetermined signal edges of a second pair of terminals (IN1 and IN2) in response to a predetermined edge (raising edge) of a predetermined terminal (IN2) and to store them to an input/output memory in the PLC apparatus.
In the drawing, since the operation codes, MOV, SEND, and INC, are well known to a person skilled in the art, explanation for those is omitted here. Further, in the rectangle blocks surrounding the operation codes, a large number of arrays of instruction words required to realize necessary functions are listed in actual.
Therefore, when a plurality of remote input/output apparatuses exist and a plurality of subjects of deterioration diagnosis exist in each apparatus, programs shown in FIG. 10 for respective subjects of deterioration diagnosis is required to be written in user program, so that large amount of effort is required. In addition, when a program for such logging process is added, entire volume of the user program is increased. Accordingly, cycle time in the PLC apparatus will be slightly varies from the cycle time when the system is operative and reliability of time lag data obtained in such condition cannot be always assured.
The present invention has been made in view of the above problems and has an object of reducing effort for determining a threshold value, for example, at an introduction of PLC system including the above type of external equipment deterioration diagnosis function and collecting data with high reliability by maintaining constant operation even when system is being introduced or operative.
Other objects and effects of the present invention will be appreciated easily by a person skilled in the art with reference to the following description of the specification.